1. Field of the Invention
The present invention relates to an information record medium such as a DVD disc, on which audio information of music and the like which are different in the recording methods or encoding methods are recorded, and a reproducing apparatus for reproducing the audio information and the like.
2. Description of the Related Art
There is a video DVD (which is a disc conformable to a DVD-Video standard) as a recording medium for recording video information such as a movie and the like. The video DVD is used as a recording medium for recording the movie and the like, since it has a large capacity.
There is an audio DVD (which a disc conformable to a DVD-Audio standard) to record only the audio information such as a music and the like but not the video information such as the movie and the like. In a case of this audio DVD, the audio information corresponding to a plurality of CDs (Compact Discs) can be recorded on a single audio DVD, because of its large capacity as the DVD. In addition to the video information such as the movie and the like, the audio DVD can also record the audio information corresponding to a music CD that is a sound track version of that movie.
It is intended that the audio DVD mainly records the audio information such as a music and the like, and also enables the reproduction of unprecedented multi-channel. Moreover, it is intended that the audio DVD enables the reproduction of unprecedented high quality even as not only the multi-channel but also a two-channel stereo.
In such a DVD audio disc, if only the audio information of the multi-channel is recorded, this results in such a problem that a user having the two-channel reproducing apparatus can listen to only a part of the sound thereof, or the reproduction cannot be performed at all.
So, it is necessary to record the audio information for the two-channel reproduction together with the audio information for the multi-channel reproduction on the disc, in order for even the user having only the reproducing apparatus dedicated to the two-channel to enjoy this disc.
However, in this case, these two kinds of audio information are duly the same title and the same song. Thus, recording these two kinds of audio information as they are on the disc leads to the existence of the two kinds of titles having the same name and songs having the same name. Hence, this results in a first problem that the user is confused. This first problem is similarly brought about not only in a case when a reproducing manner of the channel and the like is different, but also in a case when a recording manner such as a binaurally recording operation and the like is different, in a case when an encoding method such as an AC-3 and the like is different and in a case when a combination of the reproducing manner, the recording manner or the encoding method is different.
Next, in an already-standardized DVD video format, a plurality of audio information can be recorded together with video information, at the same time. For example, it is possible to switch between a voice of an original language and a voice dubbed in Japanese, for a certain movie. Similarly, it is also possible to switch between an LPCM stereo voice and an AC-3 multi-channel voice, under the same title. Thus, the plurality of audio information can be treated as the same title and the same song. Hence, it is possible to change an audio stream to thereby change the kind of audio information to be reproduced.
On the other hand, it is desired to record the video information even on the audio DVD, so as to record the video information such as a menu and additional information. In this case, if an image is recorded by using a method different from the DVD video format, this cannot attain the compatibility with the video format. It is desirable to reproduce a portion where the image is attached on the audio disc, even for a video player which is presently marketed.
Thus, from these viewpoints, it is desirable that the structure to record the substantial information containing the image is similar to that of the DVD video format.
However, in order to achieve that structure, it is necessary to multiplex a plurality of kinds of audio information and then record them on the disc as one object. Also, in order to manage a plurality of streams, it is necessary that management information is included in the data. Thus, the case of having the same structure as the video format reduces the process necessary for the switching operation of the reproducing apparatus at the time of the reproduction. However, this case brings about such a trouble that the process at the time of the recording becomes complex.
The performance for the recording operation and the conformity with a presently-used studio unit are significant, and the non-complex process in the recording operation are desired for the audio format. In particular, the structure that the management information is not included in the data is desired.
Thus, there are two kinds of structures i.e., a structure peculiar to the DVD audio format in the case of recording only the audio information and a structure conformable to the DVD video format containing the image. When only the audio information is reproduced for the data having the two kinds of structures, there are the two kinds of formats, which are completely different from each other, in the reproduction control information, unless the logical structures are common. Hence, the process in the reproducing apparatus becomes heavy, which cannot provide a unified operation. Therefore, this results in a second problem that the user is confused.